Tamper resistant engine governor

ABSTRACT

An engine governor is made resistant to tampering or unauthorized modification of speed settings by providing a cover and a guard for the speed setting and control mechanism. The cover and guard are retained by bolts set in recesses and protectable by plugs retained by pins installed after installation of the governor on the engine and adjustment of the speed settings. However, the pins are positioned so they may not be removed without first removing the governor from the engine.

United States Patent Hebb, Jr. et al. 1 July 8, 1975 TAMPER RESISTANT ENGINE GOVERNOR 3,400,697 9/1968 Cupit et al. 123/97 R 695 244 10 1972 V II I23 RV [75] Inventors: Edwin E. Hebb, Jr., Dearborn; l 8 I97 E g a: g Umon Lake Primary Examiner-Charles J. Myhre O O Assistant Examiner-William C. Anderson [73] Assignee: General Motors Corporation, Attorney, Agent, or Firm-Robert .1. Outland Detroit, Mich.

22 Filed: May 31, 1974 [57] ABSTRACT An engine governor is made resistant to tampering or [2]] App! 474969 unauthorized modification of speed settings by providing a cover and a guard for the speed setting and con- [52] US. Cl. 123/195 C; 123/97 R; 123/198 E trol mechanism. The cover and guard are retained by [51] Int. Cl F02f 7/00 bolts set in ss s an pr t table y plugs retained [58] Field of Sear h 123/195 C, 97 R, 198 E by pins installed after installation of the governor on the engine and adjustment of the speed settings. How- [56] Refer Cit d ever, the pins are positioned so they may not be re- UNITED STATES PATENTS moved without first removing the governor from the 2,893,363 7/1959 Bettoni 123/97 R engme 3,103,209 9/1965 Bekkala et al. 123/97 R X 3 Claims, 4 Drawing Figures SHEET Em a m,

1 TAMPER RESISTANT ENGINE GOVERNOR FIELD OF THE INVENTION This invention relates to internal combustion engines and, more particularly, to engine governors having cover means resistant to tampering with pre-set governor speed settings.

BACKGROUND OF THE INVENTION It is known in the art relating to mechanical engine governors to provide means for adjusting the speed settings of the governor in order to provide proper operation of the engine controlled by the governor in its particular application. Such adjusting means are commonly placed in an exposed position or under an easily removable cover so that speed adjustments may be made without difficulty.

However, in some engine applications, as for example in highway trucks, it has been found desirable for reasons of engine durability and operating economy to discourage resetting of the governed speeds by unauthorized persons.

SUMMARY OF THE INVENTION The present invention provides guard and cover means for use with a speed limiting mechanical governor and arranged to resist tampering by unauthorized adjustment of the speed settings. The guard and cover are retained in place by threaded bolts which, after initial setting of the governor speeds, are covered by plugs that prevent access to the bolt heads. The plugs are then pinned in place in a manner which prevents their removal unless the governor is first removed from the engine. In this way, access by unauthorized persons to the governor speed setting and control mechanism is made sufficiently difficult to resist or discourage unauthorized attempts to re-set the speeds.

These and other features and advantages of the invention will be more fully understood from the following description of a preferred embodiment taken together with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings:

FIG. 1 is an end view of an internal combustion engine having governor means according to the invention;

FIG. 2 is an enlarged view of the engine of FIG. 1 showing details of the engine governor and its relation to the blower housing on which it is mounted;

FIG. 3 is a longitudinal cross-sectional view showing portions of the governor speed adjusting and control mechanism protected by guard and cover means according to the invention as viewed from the plane indicated by the line 3-3 of FIG. 2; and

FIG. 4 is a top view from the plane indicated by the line 4-4 of FIG. 3 with portions of the governor inspection cover removed to show the arrangement of the internal guard.

DESCRIPTION OF THE ILLUSTRATED EMBODIMENT In the drawings, numeral generally indicates an internal combustion engine of the two-stroke diesel type. Engine 10 conventionally includes a cylinder block 12 having a pair of spaced angularly disposed cylinder heads l3, 14, all having conventional internal opcrating components (not shown).

On the top of the block 12 and centered between the cylinder heads l3, 14, there is mounted a Roots type blower 16 having a housing 17 enclosing a pair of rotors 18 which are driven by the engine to provide charging and scavenging air in conventional fashion. On one end of the blower housing, a limiting speed mechanical governor 20 is mounted with its internal mechanism connected so as to be driven by the blower in known fashion.

Except for the novel guard and cover arrangement to be subsequently described, the governor comprises a limiting speed mechanical governor of a type in common use on Models 6V and 8V-7l GM diesel engines. The conventional parts of the governor include a body 22 enclosing a-speed responsive fly-weight mechanism (not shown) connected through suitable linkage with a bell crank 24 rotatable on a center 25 and connected by a pin 26 with a differential lever 28. Lever 28 in turn connects through link 29 with the injector fuel racks (not shown) of the engine and also has a bifurcated portion which captures a pin 30 connected with a manual throttle control actuatable by the operator of the vehicle in which the engine is installed.

Bell crank 24 also carries an adjusting screw 32 which engages the low speed spring cap 33 of the governor speed setting and control mechanism generally indicated by numeral 34. Mechanism 34 includes a low speed spring 36 engaging the cap 33 and a high speed plunger 37 engageable by the cap upon compression of the spring 36. Plunger 37 is slidably received within the governor body and engages a high speed spring 38 which biases the plunger toward a low speed position against the body 22, as shown in FIG. 3.

The high speed spring 38 is compressed by a cupshaped retainer 39 that is threadably received in an opening 40 of the governor body 22 for adjustment of the high speed spring compression to control the maximum engine speed. Idle speed is controlled by compression of the low speed spring 36 by a rod-like adjusting screw 41 carrying a spring seat 42 and threadably received in an extended end portion of the high speed plunger 37 which protrudes through the end of the high speed spring retainer 39. Nuts 44 and 45 are provided for locking the retainer 39 and adjusting screw 41, respectively, in their desired positions.

As may be seen, the speed setting and control mechanism of the governor extends through the threaded opening 40 in which the retainer 39 is received so that portions of the mechanism are located within the governor body and other portions extend exteriorly thereof. A removable inspection cover 48 is mounted on the governor body to provide access to the body interior for inspection and adjustment of the governor. In addition, a protective cover 49 is mounted on the governor body enclosing the speed adjusting portions of the control mechanism which protrude outside of the body.

The novel features of the present invention include the provision of a guard 50, as well as certain features of construction and installation of the guard 50 and protective cover 49, which are provided to deter unauthorized readjustment of the governor speed settings when the engine is in service.

The guard 50 comprises a shaped metal shield 52 which covers the operating portions of the speed control mechanism inside the governor body to prevent tampering therewith (such as by inserting shims) when the inspection cover 48 is removed. A securing portion 53 formed with the shield includes a threaded opening 54 for retaining the guard 50 in place, as will be subsequently described.

The protective cover 49 includes an elongated body having an axially extending cylindrical pocket 56 for enclosing the portions of the governor speed setting mechanism extending outside of the governor body. Above and below the pocket 56 there are provided enclosed bolt receiving openings 57, 58 which extend longitudinally through the cover to recesses 60, 61 provided in enlarged boss portions 63, 64, respectively, located on the outer end of the cover 49.

Securing bolts 66, 67 are received within the openings 57, 58, respectively, with their head portions 68 engaging washers 69 at the bottoms of the recesses 60, 61. Bolt 67 engages a threaded opening 70 in the governor body 22, while bolt 66 is made longer, extending through an opening 71 in a wall of the governor body and into engagement with the threaded opening 54 of the guard 50. in this way, bolt 66 serves both to assist in retaining the cover 49 in position on the exterior of the governor body while also retaining the guard 50 in its position within the governor body.

As is best seen in FIGS. 2 and 3, the boss portions 63, 64 are interconnected by a thickened web 72, while boss portion 64 includes an extended portion 74 for a purpose which will shortly become clear. Pin receiving openings 75, 76 are provided in the bosses. Openings 75 extends vertically through bosses 63 and 64 and the connecting web 72, while opening 76 extends transversely of the engine horizontally through boss 64 and the extended portion 74 and intersecting the plane of opening 75 at the center of the recess 61.

Plugs 78 and 79 are loosely received within the recesses 60, 61, respectively, seating against shoulders 80 provided outwardly of the bolt heads 68. The plugs are each provided with taper pin receiving openings 82, 83, respectively, which are respectively aligned with the openings 75, 76. A taper pin 85 is driven into the vertical opening 75 from the upper end and extends through the plug opening 82 so as to prevent removal of the plug and the securing bolt 66 until the plug 85 is driven out by inserting a drift pin or the like through the bottom end of the opening 75. In like fashion, a taper pin 86 is driven into opening 76 from the outer end extending through opening 83 of the plug 79 and preventing removal of that plug and, therefore, bolt 67 until such time as the pin 86 is driven out of the opening by inserting a drift pin or the like from the inner end of the opening 76.

The protective cover 49 and its boss portion 64 are positioned so that the extended portion 74 is located closely beside a rib 88 that forms a wall of the housing 17 of the engine blower 16. Opening 76 through the extended portion 74 has its inner end disposed closely against the rib 88, preventing the insertion of a drift pin to remove the taper pin 86 until such time as the governor is removed from the blower housing 17. In similar fashion, the plug 79 closes the lower end of the opening 75, preventing the insertion of a drift pin for the removal of taper pin 85 until such time as the plug 79 is removed, which can only be done upon removal of the pin 86. The removal of pin 85 is further hindered by the proximity of blower housing 17 and cylinder head 13 which prevents a drift pin from being driven from below. Thus, the arrangement of the plugs and pins in the protective cover 49 prevents the removal of the retaining bolts 66, 67 and, therefore, the protective cover 49 and guard 50 without first removing the governor from its position on the blower housing.

Upon initial construction or overhaul of a governor and its application to an engine, the plugs and pins are omitted from the installation until such time as the engine has been placed in its final application. At this time, the protective cover and guard may be removed for proper adjustment of the engine speed settings of the governor. Thereafter, the guard 50 and cover 49 are reinstalled and secured in place by the bolts 66, 67. Then the locking plugs 78, 79 and pins 85, 86 are installed to prevent unauthorized removal of the cover and guard and tampering with the speed setting. As a result, unauthorized readjustment of governor speed after the engine has been placed in service is rendered substantially more difficult than in the case of conventional arrangements, wherein an easily removable cover is provided.

While the invention has been described by reference to a specific embodiment, it should be understood that numerous changes may be made without departing from the spirit and scope of the inventive concepts disclosed and, accordingly, the invention is intended to be limited only by the language of the following claims.

What is claimed is:

1. The combination in an internal combustion engine of:

an engine driven component having a housing,

an engine governor including a body mounted on said housing and having means for adjusting the governor speed settings,

a protective cover mounted on said governor body, said cover extending adjacent said component housing and enclosing said governor speed setting adjusting means,

means securing said cover to said governor body, said securing means being received in recesses in said cover, said recesses being formed in adjacent boss portions of said cover and one of said boss portions extending adjacent said component housing,

removable plugs closing said recesses and preventing removal of said securing means without removing said plugs, said plugs being retained by pins driven into openings through said plugs and boss portions, at least one of said openings having one end blocked by adjacency to said component housing, said one opening having its pin installed from its other end and removable only by driving out from said blocked end, whereby said protective cover may be installed after installation of said governor on said component but, after installation of said plugs and pins, said governor must be removed from said component in order to remove said protective cover for readjustment of the governor speed settings.

2. The combination of claim 1 wherein another of said openings intersects said one opening and its respective plug, said other opening being blocked by the plug retained by the pin installed in said one opening, said other opening also having its pin installed from its unblocked end and removable only by driving out from its blocked end.

3. An internal combustion engine having a housing supporting an engine driven governor, said governor comprising:

a body,

speed control mechanism in said body and including speed adjusting means extending externally of said body, said speed control mechanism having an internal portion also susceptable of speed adjustment,

an inspection cover closing said body adjacent said speed control mechanism internal portion but removable for inspection and servicing thereof,

a removable guard within said body and covering said internal portion to prevent speed adjustment thereof while said guard is in place,

a protective cover mounted on the exterior of said body and enclosing the external portion of said speed adjusting means, preventing external speed adjustment while said protective cover is in place,

threaded means securing said cover to said body, at least one of said threaded means extending through said cover and engaging said removable guard to retain said guard in place until removal of said one threaded means, said threaded means being received in and removable only through recesses in said protective cover,

plugs closing the ends of said recesses and blocking removal of said threaded means,

drilled openings extending transversely through said plugs and said cover and pins received in said openings and extending through said plugs, preventing their removal from said cover, said pins being driven into said openings from one of their ends and removable only by driving out from the other of their ends, said openings intersecting such that the pin in said one opening blocks the other end of said other opening and blocks removal of the pin from the other opening, said other opening being positioned so that its other end is blocked by a portion of the engine housing on which it is installed such that when said plugs and pins are installed, said guard and coveer may be removed from said governor only when said governor is removed from said engine. 

1. The combination in an internal combustion engine of: an engine driven component having a housing, an engine governor including a body mounted on said housing and having means for adjusting the governor speed settings, a protective cover mounted on said governor body, said cover extending adjacent said component housing and enclosing said governor speed setting adjusting means, means securing said cover to said governor body, said securing means being received in recesses in said cover, said recesses being formed in adjacent boss portions of said cover and one of said boss portions extending adjacent said component housing, removable plugs closing said recesses and preventing removal of said securing means without removing said plugs, said plugs being retained by pins driven into openings through said plugs and boss portions, at least one of said openings having one end blocked by adjacency to said component housing, said one opening having its pin installed from its other end and removable only by driving out from said blocked end, whereby said protective cover may be installed after installation of said governor on said component but, after installation of said plugs and pins, said governor must be removed from said component in order to remove said protective cover for readjustment of the governor speed settings.
 2. The combination of claim 1 wherein another of said openings intersects said one opening and its respective plug, said other opening being blocked by the plug retained by the pin installed in said one opening, said other opening also having its pin installed from its unblocked end and removable only by driving out from its blocked end.
 3. An internal combustion engine having a housing supporting an engine driven governor, said governor comprising: a body, speed control mechanism in said body and including speed adjusting means extending externally of said body, said speed control mechanism having an internal portion also susceptable of speed adjustment, an inspection cover closing said body adjacent said speed control mechanism internal portion but removable for inspection and servicing thereof, a removable guard within said body and covering said internal portion to prevent speed adjustment thereof while said guard is in place, a protective cover mounted on the exterior of said body and enclosing the external portion of said speed adjusting means, preventing external speed adjustment while said protective cover is in place, threaded means securing said cover to said body, at least one of said threaded means extending through said cover and engaging said removable guard to retain said guard in place until removal of said one threaded means, said threaded means being received in and removable only through recesses in said protective cover, plugs closing the ends of said recesses and blocking removal of said threaded means, drilled openings extending transversely through said plugs and said cover and pins received in said openings and extending through said plugs, preventing their removal from said cover, said pins being driven into said openings from one of their ends and removable only by driving out from the other of their ends, said openings intersecting such that the pin in said one opening blocks the other end of said other opening and blocks removal of the pin from the other opening, said other opening being positioned so that its other end is blocked by a portion of the engine housing on which it is installed such that when said plugs and pins are installed, said guard and coveer may be removed from said governor only when said governor is removed from said engine. 